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authorAndrew G. Morgan <morgan@kernel.org>2008-01-21 17:18:30 -0800
committerLinus Torvalds <torvalds@woody.linux-foundation.org>2008-01-21 19:39:41 -0800
commita6dbb1ef2fc8d73578eacd02ac701f4233175c9f (patch)
treeeb2efa0193cdc7ab6b1f30068571194d0dabf230 /security
parenta10336043b8193ec603ad54bb79cdcd26bbf94b3 (diff)
downloadlinux-linaro-a6dbb1ef2fc8d73578eacd02ac701f4233175c9f.tar.gz
Fix filesystem capability support
In linux-2.6.24-rc1, security/commoncap.c:cap_inh_is_capped() was introduced. It has the exact reverse of its intended behavior. This led to an unintended privilege esculation involving a process' inheritable capability set. To be exposed to this bug, you need to have Filesystem Capabilities enabled and in use. That is: - CONFIG_SECURITY_FILE_CAPABILITIES must be defined for the buggy code to be compiled in. - You also need to have files on your system marked with fI bits raised. Signed-off-by: Andrew G. Morgan <morgan@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@akpm@linux-foundation.org>
Diffstat (limited to 'security')
-rw-r--r--security/commoncap.c13
1 files changed, 10 insertions, 3 deletions
diff --git a/security/commoncap.c b/security/commoncap.c
index 5bc1895f3f9..ea61bc73f6d 100644
--- a/security/commoncap.c
+++ b/security/commoncap.c
@@ -59,6 +59,12 @@ int cap_netlink_recv(struct sk_buff *skb, int cap)
EXPORT_SYMBOL(cap_netlink_recv);
+/*
+ * NOTE WELL: cap_capable() cannot be used like the kernel's capable()
+ * function. That is, it has the reverse semantics: cap_capable()
+ * returns 0 when a task has a capability, but the kernel's capable()
+ * returns 1 for this case.
+ */
int cap_capable (struct task_struct *tsk, int cap)
{
/* Derived from include/linux/sched.h:capable. */
@@ -107,10 +113,11 @@ static inline int cap_block_setpcap(struct task_struct *target)
static inline int cap_inh_is_capped(void)
{
/*
- * return 1 if changes to the inheritable set are limited
- * to the old permitted set.
+ * Return 1 if changes to the inheritable set are limited
+ * to the old permitted set. That is, if the current task
+ * does *not* possess the CAP_SETPCAP capability.
*/
- return !cap_capable(current, CAP_SETPCAP);
+ return (cap_capable(current, CAP_SETPCAP) != 0);
}
#else /* ie., ndef CONFIG_SECURITY_FILE_CAPABILITIES */